BUG: External preview doesn't reopen when search window is toggled

### Checks

- [x] I have checked that this issue has not already been reported.

- [x] I am using the latest version of Flow Launcher.

- [ ] I am using the prerelease version of Flow Launcher.

### Problem Description

If you toggle the search window (Main Window) while having a preview-able result selected and using external previews, the external preview doesn't reappear with the search window.
Instead it falls back to an internal preview

### To Reproduce

1. Setup External previews (install quicklook app and plugin) and turn on always preview
2. select preview-able result (quicklook should show up)
3. close and reopen search window

### Screenshots

_No response_

### Flow Launcher Version

2.1.3

### Windows Build Number

10.0.26200.8894

### Error Log

_No response_

Reproduce the issue using an external preview with the QuickLook app and plugin enabled, then toggle the Flow Launcher search window while a previewable result is selected. Trace the external-preview and main-window toggle flow; done means reopening the search window restores the external preview instead of falling back to an internal preview.

Written by the indexing model from the issue text.